Method of fumigating



Patented Jan. 4, 1927.

UNITED, STATES I 1,613,590 PATENT OFFICE,

WALTER S. LANDIS, 0F WHITE STONE LANDING, NEW YORK, AND GUY H. BUCHANAN, OF WES'IFIELD, NEW JERSEY, ASSIGNORS TO AMERICAN CYANAMID COMPANY,- OF NEW YORK, N. Y., A CORPORATION OF MAINE.

A METHOD or FUMIGATING.

are at present in wide use, to the end that,

they may be made more eiiicient and more safe for those engaged in carrying them out.

With these and other objects in view, the invention consists in the novel steps and combinations of steps constituting the process,.all as will be more fully hereinafter disclosed and particularly pointed out in the claims. 7

In order that the invention may be the more clearly understood, it is said:

In the fumigation of enclo'ied spaces with highly poisonous fumigants such, for example, as hydrocyanic acid gas, the fumigant is introduced into the enclosure either by atomizing the liquid acid and permitting it to gasify, or by the direct generation of the gas within the enclosed space as by a chemical reaction between sulphuric acid and sodium cyanide. In -these methods, the gas is employed in such quantity that when thoroughly diffused through the space, there will be a volume concentration of from onefourth of on per cent to one per cent, depending upon the kind of pest to be eradicated. i

In such dilute form, hydrocyanic-acid gas possesses little odor, and therefore, its presence cannot bereadily detected without chemical tests, although the quantities'actually presentmay be sufficient to almost instantly kill a human being who attempts to breathe the gas mixture. As a result, fumigation by these methods has been accompanied by manyfatalities, either due to persons being in the space to befumigated at the time the hydrocyanic acid gas' is introduced, or by persons walking into the enclosure after the hydrocyanic acid gas has been introduced, and before the QIlOlOTGtl space has been thoroughly ventilated.

On the other. hand, we have found through experiments that certain gases when mixed with hydrocyanic acid gas have little or no chemical efiect on the latter when in a dilute form. Yet these said dilute gases will. nevertheless, be suliicient to cause sneezing, difficult breathing, and other unpleasant sensations without actually endan- 1921. Serial No. 483,261.

gering human life. Ammonia is one of such gases. vention we, previous to the introduction of the hydrocyanlc gas, fill the space to be Therefore, in carrying out this infumigated with ammonia gas having a concentration of, say, one 'per cent or less.

This dilute ammonia gas will rapidly (lit fuse throughout the space to be. fumigated,, I and its pungent odor as well as the-other efl'ects above mentioned will serve as an efi'ectlve warning to any person therein, and W111 cause him to seek outside alr.

A suitable time after the introduction of the said ammonia, for example, say, one-- half hour, we then introduce hydrocyanic acid gas or other fumigant in suitable dos-' age and maintain the vspace closed up for a suitable period of say one or two hours, or untilthe pests are eradicated. We may then open the space to the outside air and through effective ventilation remove the hydrocyanic acid or we may destroy the acid remaining within the enclosure in any suitable manner, as for example, by the method disclosed in our patent dated November 3, 1925, No. 1,559,892, entitled Process of fumigating.

. The pungent odor of the ammonia will al o serve as a means of warning until it is safe to again enter the space which has been also serves as awarning after fumigation is complete, or during its performance, to keep persons from entering the space before it IS safe. to do so. In this manner, we can avoid the many fatalities that are now continually occurring, particularly in the fumigation of ski in our various harbors.

In case It is desired to use the proce% of our said copending application for the destructlon or neutralization of the hydrocyanic' acid after the fumigationjs complete, should the quantity of ammonia added hefore fumisating have been reduced by leakage, an a diti'onal quantity of NH suflicientto makeup the'deficiency, ig'any exists I overthat-needed for destruction, may be introduced after fumigation is complete. If an excess of ammonia 1s used, even in the case of. use of our method of destruction of tl1eliydrocyanic acid, that excess will serve the useful purpose of providing the aftervWarning. I

It is obvious that those skilled in the art may vary the details of the procedure without departing from the .spirit of the invention, and therefore we do not wish to be limited to the above disclosure except as may I berequired by the claims.

What we claim is:

1. The method of fumigating with a highly poisonous inodorous fumigant which consists in introducing ammonia into the space to be fumigated to serve as a warning of the intended fumigation; and introducing said fumigant into said space, substantially as troducing said fumi ant into said space,

substantially as described.

3. The method of fumigating with a highly poisonous inodorous fumigant which con- EiStS in first introducing ammonia into thev space to be fumigated to produce a concentration ofless than 5% to serve as a Warning of the intended fumigation; and subsequently introducing said fumigant into said space, substantially as described.

In testimony whereof we aflix our signatures.

WALTER S. LANDIS. GUY H. BUCHANAN. 

